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United States Patent | 6,181,430 |
Meyer ,   et al. | January 30, 2001 |
An interferometer having a light beam source that produces a plurality of separate and distinct wavelengths of light. Optic fibers are used to transport the wavelengths of light toward an object surface and to allow light reflected from the object to pass through a polarizer to improve the polarization ratio of the reflected light to determine a characteristic of the object surface.
Inventors: | Meyer; William V. (Lakewood, OH); Smart; Anthony E. (Costa Mesa, CA) |
Assignee: | Ohio Aerospace Institute (Brook Park, OH) |
Appl. No.: | 270202 |
Filed: | March 15, 1999 |
Current U.S. Class: | 356/495; 356/511 |
Intern'l Class: | G01B 009/02 |
Field of Search: | 356/357,359,360,349,351,489,495,511,512 |
4534649 | Aug., 1985 | Downs. | |
4576479 | Mar., 1986 | Downs. | |
5127731 | Jul., 1992 | De Groot | 356/359. |
5159408 | Oct., 1992 | Waldenmaier et al. | 356/357. |
5270560 | Dec., 1993 | Cheng. | |
5293215 | Mar., 1994 | Pfendler et al. | 356/360. |
5398113 | Mar., 1995 | de Groot. | |
5404221 | Apr., 1995 | de Groot. | |
5473434 | Dec., 1995 | de Groot. | |
5481360 | Jan., 1996 | Fujita. | |
5488477 | Jan., 1996 | de Groot. | |
5526116 | Jun., 1996 | de Groot. | |
5671050 | Sep., 1997 | de Groot. | |
5708279 | Jan., 1998 | Cheng. |
Article entitled "Three-Wavelength Interferometry" from the Internet. "Interometric Laser Profilometer for Rough Surfaces," de Groot, 1991. "Use of Multimode Short-External-Cavity Laser Diode for Absolute-Distance Interferometry," de Groot, 1993. "Synthetic Wavelength Stabilization for Two-Color Laser-Diode Interferometry," de Groot, 1991. "Three Color Laser Diode Interferometer," de Groot, 1991. "Digital Wave-front Measuring Interferometry: Some Systematic Error Sources," Schwider, 1983. "Progress In Absolute Distance Interferometry," Gillard, 1983. "Integrated Acoustically-tuned Optical Filters for Filtering and Switching Applications," Smith, 1991. "Sampling of Quadrature-Phase Quantities," Harnefors 1995. "Measurement of the Profiles of `Super-Smooth` Surfaces Using Optical Interferometry," Downs 1988. "Optical System For Measuring the Profiles of Super-Smooth Surfaces," Downs 1985. "A Proposed Design for an Optical Interferometer With Sub-nanometric Resolution," Downs 1990. "Optical Techniques to Solve the Signal Fading Problem in Fiber Interferometers," Sheem, 1982. "Optical Ranging By Wavelength Multiplexed Interferometry," Williams 1986. "Absolute Optical Ranging with 200-nm Resolution," Williams 1989. "Multiple-wavelength Phase-shifting Interferometry," Cheng 1985. "Synthetic-Heterodyne Interferometric Demodulation," Cole, 1982. |